Understood. In Stock form it is not possible to run full e85 due to limitations in fuel trims. But for now, until some sort of live tuning is available, i am look for post failures. Most cars after the obdII regulations are made not to be bothered by the slight increase of corrosivness of ethanol. We can already run e10 without issue.
That being said, a mixture that stays within your fuel trims, and still keeps your idc well below 100 should work fine imho.
On my subaru, we tricked the ecu into thinking it had different sized injectors. This change could be made real time. And because the O2 sensor looks for lambda, not afr your system ran fine. Lambda is the same across ethanol, methanol, and gas. But 1 lambda is not the same afr across those fuels.
With all that being said, a 30% mixture is what I still run on my subaru now. It didn't affect mpg (which was bad due to the new gearing) but added some low end touque and lowered egts a bit. And I am hoping the same can be done for the optima and forte turbos.